Low nox burner apparatus and method

Abstract

Combustor apparatus and methods providing increased internal flue recirculation for reducing NO x emissions by injecting a series of surrounding primary fuel streams outside the combustor wall toward the combustor combustion section and also injecting one or more subsequent series of surrounding fuel streams, where each subsequent series of surrounding fuel streams must travel a further distance to reach the combustion zone and each series of surrounding fuel streams must contact one or more radial impingement structures disposed on the outside of the combustor wall.

Description

[0001] Related Cases

[0002] This application claims the benefit of U.S. patent application Ser. No. 16 / 568,519, filed Sep. 12, 2019, and is hereby incorporated by reference into this document as if fully set forth herein. Technical Field

[0003] The present invention relates to burner apparatus and methods for reducing NO from heaters, boilers, incinerators, other combustion heating systems, and other combustion systems of the type used in refineries, power plants, and chemical plants, and in other industrial services and facilities. x emission. Background Art

[0004] Will significantly reduce NOx from heaters, boilers, incinerators and other combustion systems used in industrial processes x There is a continuing need for vented burners and burner combustion methods.The improved burners would also preferably provide flame length, turndown ratio, and stability levels that are at least as good as or better than those provided by current burner designs.

[0005] For burners used in industrial applications, if the burner fuel is thoroughly mixed with air and combustion occurs under ideal conditions, the combustion products produced are primarily carbon dioxide and water vapor. However, when the fuel is burned under less than ideal conditions, such as at high flame temperatures, the nitrogen present in the combustion air reacts with oxygen to produce nitrogen oxides (NO x ). Under the same conditions, NO x The production of NO increases with the increase of the temperature during the combustion process. x Emissions are generally believed to contribute to ozone depletion, acid rain, smog, and other environmental problems.

[0006] For gaseous fuels without fuel-bound nitrogen, thermal NO x Yes No x The main mechanism of production. When the flame reaches a high enough temperature to break the covalent N2 bond, the resulting "free" nitrogen atoms will bond with oxygen to form NO x When the thermal NO x .

[0007] Typically, the temperature of combustion is not high enough to break all of the N2 bonds. Instead, most of the nitrogen in the air stream passes through the combustion process and remains in the combustion products as diatomic nitrogen (N2). However, some N2 will typically reach a high enough temperature in the high-intensity region of the flame to break the N2 bonds and form "free" nitrogen. Once the covalent nitrogen bonds are broken, "free" nitrogen becomes available to bond with other atoms. Fortunately, the free nitrogen will most likely react with other free nitrogen atoms to form N2. However, if another free nitrogen atom is not available, the free nitrogen will react with oxygen to form NO x .

[0008] As the burner flame temperature increases, the stability of the N2 covalent bond decreases, causing an increase in the production of free nitrogen and, therefore, also an increase in thermal NO x Therefore, in reducing NO x In the ongoing effort to reduce emissions, various types of burner designs and theories have been developed with the goal of lowering peak flame temperatures.

[0009] The diverse demands of refining, power generation, petrochemical processes, and other processes necessitate the use of many different types and configurations of burners. x The method of emission may vary depending on the application. However, thermal NO x Reducing combustion is typically accomplished by slowing the combustion rate. Since combustion is a reaction between oxygen and the burner's fuel, the goal of delaying combustion is typically to reduce the rate at which the fuel and oxygen mix and burn. The faster the oxygen and fuel mix, the faster the combustion rate and the higher the peak flame temperature.

[0010] To reduce NO x Examples of different types of burner design approaches for emissions have included:

[0011] (a) Staged air design, in which the combustion air is usually divided into two or more streams to form different stages of lean burn and rich burn;

[0012] (b) designs using internal flue gas recirculation (IFGR), in which internal flow momentum is used to recirculate some of the flue gas (i.e., inert combustion products) in the combustion system back into the combustion zone to form a diluted combustion mixture that burns at a lower peak flame temperature;

[0013] (c) A staged fuel design in which (i) all or a portion of the fuel is introduced outside the combustion air stream to delay mixing of the fuel with the combustion air stream, thereby producing a fuel-air mixture that burns at a lower peak flame temperature, or (ii) a portion of the fuel is introduced outside the primary flame envelope to stage the flame and burn the fuel in the presence of combustion products from the primary flame;

[0014] (d) Designs using external flue gas recirculation (EFGR), in which the burner typically uses an external blower that supplies combustion air to the burner and also includes an external ducting arrangement that draws flue gas from the combustion chamber into the suction portion of the blower. This flue gas mixes with the combustion air flow to reduce the oxygen concentration of the air flow supplied to the burner, which in turn reduces the peak flame temperature;

[0015] (e) Designs using "flameless" combustion in which most or all of the burner fuel is passed through and mixed with inert combustion products to form a diluted fuel that burns at a lower peak flame temperature. The mixture of fuel and inert combustion products may be up to 90% inert, resulting in a "clear" flame;

[0016] (f) Designs that use steam and / or inert injection into the burner fuel, wherein the steam or inert component is mixed with the fuel so that the resulting composition will burn at a lower peak flame temperature;

[0017] (g) Designs that use steam and / or inert injection into the combustion air stream, wherein the steam and / or inert component is mixed with the combustion air so that the resulting composition will burn at a lower peak flame temperature;

[0018] (h) Designs that use high excess air levels to dilute the products of combustion and produce low flame temperatures, such as surface-stabilized combustion burners. Summary of the Invention

[0019] The present invention provides a low NOx solution that meets the needs and alleviates the above problems. x Burner apparatus and method. The burner apparatus and method of the present invention provide significantly increased internal flue gas recirculation (IFGR) while maintaining or improving burner stability. The burner and method of the present invention will generally provide from about 16 to about 24 pounds of IFGR per pound of burner fuel and will provide significantly reduced NO in the range of from 12 ppmv to 5 ppmv or less. x Emission levels. Additionally, the burner apparatus and method of the present invention may be used in most types of fired heaters, boilers, incinerators, and other combustion systems used in industrial processes.

[0020] In one aspect, a burner apparatus for discharging a burner flame in a heating system having gaseous combustion products therein is provided. The burner apparatus preferably comprises at least: (i) a burner wall having a front longitudinal end and an exterior; (ii) a flow passage for air or other oxygen source, the flow passage extending through the burner wall and at least largely surrounded by the burner wall, the flow passage having a discharge portion at the front longitudinal end of the burner wall; (iii) a combustion zone of the burner apparatus, the combustion zone having a starting end substantially located at the front longitudinal end of the burner wall; (iv) a series of primary fuel injection structures located outside the flow passage and at least partially surrounding the flow passage, the primary fuel injection structures being located rearwardly and radially outwardly of the front longitudinal end of the burner wall and each of the primary fuel injection structures being oriented to inject a primary fuel stream toward the combustion zone along a primary fuel flow path outside the burner wall; and (v) at least one primary radial impingement structure being (i) a plurality of secondary fuel injection structures disposed on the exterior of the burner wall and located in the primary fuel flow path for contacting at least a portion of the primary fuel flow injected by each of the primary fuel injection structures; (ii) a plurality of secondary fuel injection structures disposed on the exterior of the burner wall and located in the primary fuel flow path for contacting at least a portion of the primary fuel flow injected by each of the primary fuel injection structures; (iii) a plurality of secondary fuel injection structures disposed on the exterior of the burner wall and located in the primary fuel flow path for contacting at least a portion of the secondary fuel flow injected by each of the secondary fuel injection structures; (iv) a plurality of secondary fuel injection structures disposed on the exterior of the burner wall and located in the secondary fuel flow path for contacting at least a portion of the secondary fuel flow injected by each of the secondary fuel injection structures;

[0021] In another aspect, the at least one primary radial impingement structure on the exterior of the combustor wall may optionally also be located in the secondary fuel flow path for contacting at least a portion of the secondary fuel flow injected by each of the secondary fuel injection structures.

[0022] In another aspect, the combustion zone of the burner apparatus of the present invention may optionally be a single-stage combustion zone having only one combustion stage for combusting both the primary fuel flow injected from the primary fuel injection structure and the secondary fuel flow injected from the secondary fuel injection structure.

[0023] In another aspect, the burner apparatus of the present invention may optionally further include: (a) a series of tertiary fuel injection structures located outside the flow path and at least partially surrounding the flow path, the tertiary fuel injection structures being located rearwardly and radially outwardly of the secondary fuel injection structures, and each of the tertiary fuel injection structures being oriented to inject a tertiary fuel flow toward the combustion zone along a tertiary fuel flow path outside the burner wall; and (b) at least one tertiary radial impact structure disposed on the outside of the burner wall and located rearwardly of the at least one secondary radial impact structure in the tertiary fuel flow path for contacting at least a portion of the tertiary fuel flow injected by each of the tertiary fuel injection structures.

[0024] In another aspect, a method for reducing NO from a burner apparatus is provided. x A method of discharging. The method preferably includes the steps of: (a) discharging air or other oxygen source into a combustion zone from a discharge opening of a flow passage at least partially surrounded by a burner wall, the discharge opening of the flow passage being located at a front end of the burner wall, the burner wall having an exterior, and the combustion zone having a starting end, the starting end being located substantially at the front end of the burner wall; (b) injecting primary fuel streams from a plurality of primary fuel injection structures toward the combustion zone from the burner wall exterior, wherein at least a portion of each of the primary fuel streams contacts at least one primary radial impingement structure disposed on the burner wall exterior; and (c) injecting secondary fuel streams from a plurality of secondary fuel injection structures toward the combustion zone from the burner wall exterior, wherein the secondary fuel injection structures are located rearwardly and radially outwardly of the primary fuel injection structures, at least a portion of each of the secondary fuel streams contacts at least one secondary radial impingement structure disposed on the burner wall exterior, and the at least one secondary radial impingement structure is located rearwardly of the at least one primary radial impingement structure.

[0025] In another aspect, at least a portion of each of the secondary fuel streams injected in step (c) of the method of the present invention may optionally also contact the at least one primary radial impingement structure.

[0026] In another aspect, the method of the present invention may optionally further comprise both: (i) at least a portion of each of the primary fuel streams is delivered to the starting end of the combustion zone and combusted at the starting end; and (ii) at least a portion of each of the secondary fuel streams is delivered to the starting end of the combustion zone and combusted at the starting end.

[0027] In another aspect, the method of the present invention may further include the following steps: injecting tertiary fuel streams from a plurality of tertiary fuel injection structures outside the combustor wall toward the combustion zone, wherein the tertiary fuel injection structures are located behind and radially outside the secondary fuel injection structures, at least a portion of each of the tertiary fuel streams contacts at least one tertiary radial impact structure provided on the outside of the combustor wall, and the at least one tertiary radial impact structure is located behind the at least one secondary radial impact structure.

[0028] Other aspects, features, and advantages of the present invention will become apparent to those skilled in the art upon examination of the accompanying drawings and reading the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a partially cut-away side view of Example 2 of the burner device provided by the present invention.

[0030] Figure 2 is a plan view of a burner device 2 according to the present invention. DETAILED DESCRIPTION

[0031] Before explaining the present invention in detail, it is important to understand that the present invention is not limited in its application to the details of the preferred embodiments and steps described herein. The present invention is capable of other embodiments and can be practiced or carried out in various ways. It is to be understood that the phraseology and terminology employed herein are for purposes of description and not limitation.

[0032] Furthermore, unless otherwise specified, the features, structures, and steps of the present invention discussed herein may be advantageously employed using any number or type of fuel injection tips or other structures. Additionally, the burners of the present invention described herein may be single-stage burners or burners using staged fuel and / or staged air designs.

[0033] Figure 1 and Figure 2 , a second embodiment of a burner apparatus according to the present invention is illustrated in FIG. The burner 2 of the present invention preferably includes a housing 4 that receives a flow of air or other oxygen source 6 and delivers the oxygen source flow 6 to a flow passage 8; a burner wall 10 that surrounds or at least partially surrounds the flow passage 8 for the oxygen source flow 6; and at least two (more preferably, three or more) series of fuel injection structures 12, 14, 16 that inject fuel streams 18, 20, 22 external to the burner wall 10 toward a burner combustion zone 24 that projects forwardly from the burner body 10. The burner wall 10 has a longitudinal axis 26, a rear longitudinal end 28, and a front longitudinal end 30. The flow passage 8 for the oxygen source flow 6 extends longitudinally through the burner wall 10 and has a front discharge opening 32 at the front longitudinal end 30 of the burner wall 10.

[0034] The burner 2 of the present invention is shown mounted through a wall 34 of a combustion chamber 36. The burner apparatus 2 of the present invention can be used to heat the combustion chamber 36 of generally any type of combustion heating system. The combustion chamber 36 is filled with gaseous inert combustion products (i.e., flue gas) 38 produced in the combustion chamber 36 by the burner combustion process. In addition, although the burner apparatus 2 of the present invention is Figure 1 3. Although shown as mounted horizontally in a vertical wall 34 of a combustion chamber 36, it will be understood that the burner 2 of the present invention may alternatively be mounted in the floor or ceiling of the combustion chamber 36 and may be oriented horizontally, upward, downward, or at generally any other desired operating angle.

[0035] A flow of combustion air or other oxygen source 6 is received in the housing 4 of the burner 2 of the present invention and directed into the rear longitudinal end 28 of the burner flow passage 8. The amount of combustion air or other oxygen source entering the housing 4 can be regulated, for example, by an air inlet damper 40. The oxygen source flow 6 can be provided to the housing 4 as desired by forced circulation, natural draft, a combination thereof, or in any other manner employed in the art. The oxygen source flow 6 will preferably be air that is delivered to the burner assembly 2 of the present invention by forced circulation, natural draft, a combination thereof.

[0036] As used herein and in the claims, unless otherwise indicated, it will be understood that the oxygen source stream 6 traveling through the flow path 8 of the burner 2 of the present invention can be, for example, 100% air or a mixture of combustion air and / or other oxygen sources with one or more other components, such as, but not limited to, (i) one or more externally recycled inert (i.e., non-combustible) components, such as flue gas; (ii) steam; (iii) CO2; and / or (iv) N2. However, the air or other oxygen source stream 6 preferably will not contain any fuel gas or other fuel material. Additionally, with the exception of one or more burner pilot assemblies 42a, 42b, 42c for initiating and maintaining combustion in the combustion zone 24 projecting from the front end 30 of the burner wall 10, no fuel tips or other fuel injection structures will preferably be located in or extending through the flow path 8 for the oxygen source stream 6.

[0037] The burner wall 10 is preferably constructed of a high temperature refractory burner brick material, although other structures and construction materials may alternatively be used.

[0038] As mentioned above, the burner apparatus 2 of the present invention includes two, three, four, or more series of enclosed fuel injection structures, wherein the fuel injection structures in each series (a) are located outside of the flow passage 8 for the oxygen source stream 6 and radially surround or at least partially surround the flow passage 8, and (b) inject a gaseous or liquid fuel stream, preferably a gaseous fuel stream, toward the combustion zone 24 projecting from the front end 30 of the burner wall 10. Continuing rearward from the front end 30 of the burner wall 10, each subsequent series of enclosed fuel injection structures will preferably be located rearward and radially outward of the previous series of enclosed fuel injection structures.

[0039] By way of example and not limitation, Figure 1 and Figure 2 The multiple series of fuel injection structures used in embodiment 2 of the burner device of the present invention shown in include: (1) a series of primary fuel injection tips, nozzles or other structures 12, which at least partially surround the flow path 8 and are located behind and radially outside the front end 30 of the burner wall 10; (2) a series of secondary fuel injection tips, nozzles or other structures 14, which at least partially surround the flow path 8 and are located behind and radially outside the primary fuel injection structure 12; and (3) a series of tertiary fuel injection tips, nozzles or other structures 16, which at least partially surround the flow path 8 and are located behind and radially outside the secondary fuel injection structure 14.

[0040] Each of the fuel injection structures 12, 14 and 16 may have one or more injection ports of any desired shape. Each fuel injection structure 12, 14 and 16 will preferably have only a single injection port, which will also preferably be circular in shape.

[0041] The primary fuel injection structure 12 is constructed and oriented to inject the primary fuel stream 18 as a free jet along a primary fuel flow path 48 external to the combustor wall 10 toward the combustion zone 24. The secondary fuel injection structure 14 is constructed and oriented to inject the secondary fuel stream 20 as a free jet along a secondary fuel flow path 52 external to the combustor wall 10 toward the combustion zone 24. The tertiary fuel injection structure 16 is constructed and oriented to inject the tertiary fuel stream 22 as a free jet along a tertiary fuel flow path 56 external to the combustor wall 10 toward the combustion zone 24.

[0042] As will be understood by those skilled in the art, the term "free jet," as used herein and in the claims, refers to a jet injected from a fuel tip, nozzle, or other injection structure into a fluid that is more stationary than the jet. In this case, the substantially stationary fluid is the flue gas 38 present within the combustion chamber 36. The free jets of the primary, secondary, and tertiary fuel streams 18, 20, and 22 operate to entrain the flue gas 38 and thoroughly mix the flue gas 38 with each fuel stream 18, 20, and 22 as it travels to the combustion zone 24 at the outlet end of the combustor wall 10.

[0043] The combustion zone 24 of the combustor 2 of the present invention can be a multi-stage combustion zone, or it can be a single-stage combustion zone having only a single combustion stage 58. The combustion zone 24 is preferably a single-stage combustion zone, wherein all of the primary fuel streams 18, secondary fuel streams 20, and tertiary fuel streams 22 are delivered to and combusted in the same combustion stage 58. Most preferably, at least a portion of each of the primary, secondary, and tertiary fuel streams 18, 20, and 22 is delivered to and combusted at the starting end 60 of the combustion zone 24. The starting end 60 of the combustion zone 24 is preferably located substantially at the leading end 30 of the combustor wall 10 (i.e., at or within 8 (typically 0.5) inches rearward or 0 to 60 (typically 0) inches forward of the leading end 30).

[0044] In the combustor 2 of the present invention, each fuel injection structure 12, 14, and 16 is depicted as a fuel injection tip secured to the end of a standpipe or other fuel conduit 62, 64, or 66 connected to a fuel supply manifold 68 located outside the wall 34 of the combustion chamber 36. Each fuel standpipe 62, 64, and 66 extends through the wall 34 of the combustion chamber 36 and then longitudinally through a surrounding outer skirt portion 68 of the combustor wall 10.

[0045] As the injected primary, secondary, and tertiary fuel streams 18, 20, and 22 flow around the exterior of the combustor wall 10 within the combustion chamber 36, flue gas 38 from the combustion chamber 36 is entrained within and mixed with each of the injected fuel streams 18, 20, and 22. Additionally, to stabilize and increase the amount of flue gas 38 mixed with each of the primary, secondary, and tertiary fuel streams 18, 20, and 22, and to stabilize the combustion zone 24 and the combustion flame, each of the primary, secondary, and tertiary flow streams 18, 20, and 22 is oriented and directed to contact at least one radial impingement structure formed or otherwise disposed on and around, or at least partially around, an exterior 70 of the outer skirt 68 of the combustor wall 10.

[0046] Each such impingement structure may generally be any type of obstruction that will sufficiently reduce flow momentum and / or increase turbulence of the fuel stream 18, 20, or 22 to promote smoke entrainment and mixing while allowing the resulting mixture to continue flowing to the combustion zone 24. Continuing rearwardly from the forward end 30 of the combustor wall 10, each subsequent radial impingement structure is preferably wider in diameter or width than the previous impingement structure and is located longitudinally rearwardly and laterally outwardly of the previous impingement structure.

[0047] exist Figure 1 and Figure 2 In the embodiment 2 of the burner apparatus of the present invention shown in , the radial impact structure provided on the outer portion 70 of the burner wall 10 preferably includes: (1) a front primary impact structure 72, which is located in the primary fuel flow path 48 of the primary injection structure 12, so that at least a portion of each primary fuel flow 18 contacts the front primary impact structure 72; (2) a rear primary impact structure 74, which is located behind the front primary impact structure 72 and is located in the primary fuel flow path 48 of the primary injection structure 12, so that at least a portion of each primary fuel flow 18 also contacts the rear primary impact structure 74; (3) a front secondary impact structure 76, which is located behind the rear primary impact structure 74 and is located in the secondary fuel flow path 52 of the secondary injection structure 14, so that at least a portion of each secondary fuel flow 20 contacts the front secondary impact structure 72. (4) a rear secondary shock structure 78 located rearward of the front primary shock structure 76 and in the secondary fuel flow path 52 of the secondary injection structure 14, such that at least a portion of each secondary fuel flow 20 also contacts the rear secondary shock structure 78; (5) a front tertiary shock structure 80 located rearward of the rear secondary shock structure 78 and in the tertiary fuel flow path 56 of the tertiary injection structure 16, such that at least a portion of each tertiary fuel flow 22 also contacts the front tertiary shock structure 80; and (6) a rear tertiary shock structure 82 located rearward of the front tertiary shock structure 80 and in the tertiary fuel flow path 56 of the tertiary injection structure 16, such that at least a portion of each tertiary fuel flow 22 also contacts the rear tertiary shock structure 82.

[0048] Additionally, to provide even greater amounts of IFGR and mixing in the secondary and tertiary fuel streams 20 and 22, forward and aft primary radial impingement structures 72 and 74 are preferably also located in the secondary and tertiary fuel flow paths 52 and 56 such that at least a portion of each secondary fuel stream 20 and at least a portion of each tertiary fuel stream 22 also contacts the primary radial impingement structures 20 and 22. Furthermore, additional amounts of IFGR and mixing are provided by positioning forward and aft secondary radial impingement structures 76 and 78 in the tertiary fuel flow path 56 such that at least a portion of each tertiary fuel stream 22 also contacts the forward and aft secondary radial impingement structures 76 and 78.

[0049] exist Figure 1 and Figure 2 In the embodiment 2 of the burner apparatus of the present invention shown in , the primary, secondary and tertiary radial impact structures are most preferably formed so that: (1) the front primary radial impact structure 72 is a radial protrusion formed by the front longitudinal end 30 of the burner wall 10; (2) the rear primary radial impact structure 74 is a radial protrusion formed on the outer portion 70 of the burner wall 10 and having an outer diameter (in the case of a circular burner) or a width (in the case of a square, rectangular, elliptical or other non-circular burner) that is larger than the outer diameter or width of the front longitudinal end 30 of the burner wall 10; (3) the front secondary radial impact structure 76 is a radial protrusion formed on the outer portion 30 of the burner wall 10 and having a width that is larger than the outer diameter or width of the rear primary radial impact structure 74; (4) the rear secondary radial impact structure 78 is a radial protrusion formed on the outer portion 70 of the combustor wall 10 and has an outer diameter or width greater than the outer diameter or width of the front secondary radial impact structure 76; (5) the front tertiary radial impact structure 80 is a radial protrusion formed on the outer portion 70 of the combustor wall 10 and has an outer diameter or width greater than the outer diameter or width of the rear secondary radial impact structure 78; and (6) the rear tertiary radial impact structure 82 is a radial protrusion formed on the outer portion 70 of the combustor wall 10 and has an outer diameter or width greater than the outer diameter or width of the front tertiary radial impact structure 80.

[0050] During operation of the burner 2 of the present invention, the contacting flow and momentum of the primary, secondary, and tertiary fuel streams 18, 20, and 22, and the flow and momentum of the air or other oxygen source stream 6 flowing from the front discharge opening 32 at the front end 30 of the combustor wall 10, cause reduced pressure areas to be created on the forward faces 84, 86, 88, 90, 92, and 94 of the projections or other radial impingement structures 72, 74, 76, 78, 80, and 82 provided on the exterior 70 of the combustor wall 10. These reduced pressure areas operate to increase the amount of flue gas entrained in the fuel streams, improve mixing of the fuel, flue gas, and oxygen source, stabilize the primary, secondary, and tertiary fuel streams 18, 20, and 22, and stabilize the combustor combustion zone 24 and the combustor flame.

[0051] In the burner apparatus 2 of the present invention, the riser 62 for the primary fuel injection structure 12 preferably extends forward through the surrounding outer skirt 68 of the combustor wall 10 such that (a) the primary fuel injection structure 12 is located in or at least partially forward of an opening 96 provided in the forward face 88 of the forward secondary radial impact lobe 76, and (b) the secondary fuel injection structure 14 is located in or at least partially forward of an opening 98 provided in the forward face 92 of the forward tertiary radial impact lobe 80. Thus, the primary fuel injection structure 12 preferably injects the primary fuel stream 18 forward from or substantially from the forward face 88 of the forward secondary radial impact lobe 76 toward the combustion zone 24. Similarly, the secondary fuel injection structure 14 preferably injects the secondary fuel stream 20 forward from or substantially from the forward face 92 of the forward tertiary radial impact lobe 80 toward the combustion zone 24.

[0052] like Figure 2 As shown in FIG, interstitial region 100 is disposed between primary fuel injection structures 12, which interstitial region 100 surrounds or at least partially surrounds combustor flow path 8. Similarly, interstitial region 102 is disposed between secondary fuel injection structures 14, and interstitial region 104 is disposed between tertiary fuel injection structures 16. In the combustor 2 of the present invention, secondary fuel flow 20 can be injected (a) toward or over primary injection structures 12; (b) toward or over interstitial region 100 between primary fuel injection structures 12; or (c) both. Similarly, tertiary fuel flow 22 can be injected (a) toward or over secondary fuel injection structures 14; (b) toward or over interstitial region 102 between secondary fuel injection structures 14; or (c) both.

[0053] To prevent the secondary fuel stream 20 from interfering with the injection and free jet of the primary fuel stream 18, the secondary fuel injection structures 14 are preferably offset from the primary fuel injection structures 12 such that the secondary fuel stream 20 is injected into or over the interstitial region 100 disposed between the primary fuel injection structures 12. Similarly, to prevent the tertiary fuel stream 22 from interfering with the injection and free jet of the secondary fuel stream 20, the tertiary fuel injection structures 16 are preferably offset from the secondary fuel injection structures 14 such that the tertiary fuel stream 22 is injected into or over the interstitial region 102 disposed between the secondary fuel injection structures 14.

[0054] As described above, the cross-sectional shape of the burner wall body 10 of the burner 2 of the present invention can be circular, square, rectangular, oval, or generally any other desired shape. Furthermore, while in most embodiments and applications of the burner 2 of the present invention, the burner wall 10 and two or more series of fuel injection structures 12, 14, and 16 employed in the burner 2 of the present invention will completely surround the flow passage 8 for the oxygen source stream 6, in certain applications this will not be easy. For example, the burner wall 10 and / or fuel injection structures 12, 14, and 16 may not completely surround the flow passage 8 in certain applications where the burner apparatus 2 of the present invention is used in a furnace sidewall location or must be specifically configured to provide a specific desired flame shape.

[0055] Despite Figure 1 and Figure 2 While the embodiment 2 of the burner of the present invention shown in FIG. 1 utilizes three series of surrounding fuel injection structures 12, 14, and 16, as noted above, the burner apparatus of the present invention may alternatively include only two series of surrounding fuel injection structures 12 and 14, or may have four, five, or more series of fuel injection structures. Continuing backward, each additional subsequent series of fuel injection structures will preferably be located rearward and radially outward of the previous series of fuel injection structures.

[0056] Furthermore, for each such additional subsequent series of fuel injection structures, one or more (preferably two) additional radial impingement structures for contacting the fuel stream injected by the additional series of injection structures will preferably be added to the exterior 70 of the combustor wall 10 between the added series of injection structures and the previous series of injection structures. Continuing aft, each additional radial impingement structure will preferably have a greater transverse diameter or width than the previous impingement structure.

[0057] In the method of the present invention, a stream of air or other oxygen source 6 is discharged from the discharge opening 32 of the burner flow passage 8 at the forward longitudinal end 30 of the burner wall 10 into the combustion zone 24 of the burner apparatus 2 of the present invention. Simultaneously, a primary fuel stream 18, a secondary fuel stream 20, and a tertiary fuel stream 22 are also discharged from the series of primary fuel injection structures 12, the series of secondary fuel injection structures 14, and the series of tertiary fuel injection structures 16 external to the burner wall 10 toward the combustion zone 24.

[0058] As the primary fuel streams 18 travel along the primary fuel flow path 48 outside the combustor wall 10, at least a portion of each primary fuel stream 18 contacts the aft primary radial impact bulge 74 on the exterior 70 of the combustor wall 10. Then, as the primary fuel streams 18 continue along the primary fuel flow path 48, at least a portion of each primary fuel stream 18 also contacts the forward primary radial impact bulge 72 (i.e., the forward end 30) of the combustor wall 10.

[0059] The reduced pressure area created by the momentum of the primary fuel stream 18 on the forward face 86 of the aft primary impingement projection 74, and the increased turbulence created by the contact of the primary fuel stream 18 with the aft primary impingement projection 74, operate to enhance entrainment and mixing of the gaseous combustion products 38 in the combustion chamber 36 with the primary fuel stream 18. As the primary fuel stream 18 subsequently continues to flow into the combustion zone 24, the reduced pressure area created by the momentum of the primary fuel stream 18 and the flow momentum of the oxygen source stream 6 on the forward face 84 of the forward end 30 of the combustor wall 10, and the turbulence created by the contact of the primary fuel stream 18 with the forward end 30 of the combustor wall 10, not only enhance the entrainment and mixing of the additional amount of flue gas 38 with the primary fuel stream 18, but also operate to enhance mixing of the oxygen source 6 with the primary fuel stream 18 at the starting end 60 of the combustion zone 24 and stabilize the burner flame at the combustion zone 24 and the forward end 30 of the combustor wall 10.

[0060] As the secondary fuel streams 20 travel along the secondary fuel flow path 50 outside the combustor wall 10, at least a portion of each secondary fuel stream 20 contacts the aft secondary radial impact bulge 78 on the exterior 70 of the combustor wall 10. Then, as the secondary fuel streams 20 continue along the secondary fuel flow path 50, at least a portion of each secondary fuel stream 20 also contacts the forward secondary radial impact bulge 76.

[0061] The reduced pressure areas created by the momentum of the secondary fuel stream 20 on the forward faces 90 and 88 of the aft and forward secondary impingement projections 78 and 76, and the increased turbulence created by the contact of the secondary fuel stream 20 with the aft and forward secondary projections 78 and 76, operate to enhance entrainment and mixing of the gaseous combustion products 38 with the secondary fuel stream 20.

[0062] As the tertiary fuel streams 22 travel along the tertiary fuel flow path 52 outside of the combustor wall body 10, at least a portion of each tertiary fuel stream 22 contacts the aft tertiary radial impact bulge 82 on the exterior 70 of the combustor wall 10. Then, as the tertiary fuel streams 22 continue along the tertiary fuel flow path 52, at least a portion of each tertiary fuel stream 22 also contacts the forward tertiary radial impact bulge 80.

[0063] The reduced pressure areas created by the momentum of the tertiary fuel stream 22 on the forward faces 94 and 92 of the aft and forward tertiary impingement projections 82 and 80, and the increased turbulence created by the contact of the tertiary fuel stream 22 with the aft and forward tertiary projections 82 and 80, operate to enhance entrainment and mixing of the gaseous combustion products 38 with the tertiary fuel stream 22.

[0064] In addition, it is further preferred that: (i) when the secondary fuel stream 20 travels along the secondary fuel flow path 50, at least a portion of each secondary fuel stream 20 also contacts the rear primary impact protrusion 74, and at least a portion of each secondary fuel stream 20 further contacts the front primary radial impact protrusion 72 (i.e., the front end 30) of the combustor wall 10; (ii) when the tertiary fuel stream 22 travels along the tertiary fuel flow path 52, at least a portion of each tertiary fuel stream 22 also contacts the rear secondary impact protrusion 78, and at least a portion of each tertiary fuel stream 22 further contacts the front secondary radial impact protrusion 76; and (ii) as the tertiary fuel stream 22 continues to travel along the tertiary fuel flow path 52, at least a portion of each tertiary fuel stream 22 also contacts the rear primary impact protrusion 74, and at least a portion of each tertiary fuel stream 22 further contacts the front primary radial impact protrusion 72 (i.e., the front end 30) of the combustor wall 10.

[0065] The positioning of the secondary impingement structures 78 and 76 in the flow path 52 of the tertiary fuel stream 22 and the positioning of the primary impingement structures 74 and 72 in the flow paths 50 and 52 of the secondary and tertiary fuel streams 20 and 22 operate to further enhance both: (a) the low pressure region on the leading faces 90, 88, 86 and 84 of these impingement structures and (b) the mixing of the gaseous combustion products 38 with the tertiary and secondary fuel streams 22 and 20. Additionally, the preferred positioning of the forward end 30 of the combustor wall body 10 in the flow paths 48, 50 and 52 of all of the primary, secondary and tertiary fuel streams 18, 20 and 22 provides a highly stable single-stage combustion zone 24 and flame at the forward end 30 of the combustor wall 10, wherein at least a portion of each of the primary, secondary and tertiary fuel streams 18, 20 and 22 is delivered to and combusted at the starting end 60 of the combustion zone 24.

[0066] In order to prevent the secondary fuel stream 20 from interfering with the free jet and smoke entrainment of the primary fuel stream 18, the secondary fuel stream 20 is preferably injected toward the gap region 100 between the primary fuel injection structures 12, as shown in FIG. Figure 2 In order to prevent the tertiary fuel flow 22 from interfering with the free jet and smoke entrainment of the secondary fuel flow 20, the tertiary fuel flow 22 is preferably injected toward the gap area 102 between the secondary fuel injection structures 14, as shown in FIG. Figure 2 As shown in .

[0067] Due to the increased travel distance of the exterior of the combustor wall 10 and the increased number of impingement structures contacted on the exterior 70 of the combustor wall 10, the total amount of flue gas 38 entrained in and mixed with the secondary fuel stream 20 is greater than the amount of flue gas 38 mixed with the primary fuel stream 18. Additionally, for the same reasons, the total amount of flue gas 38 entrained in and mixed with the tertiary fuel stream 22 is greater than the amount of flue gas 38 mixed with the secondary fuel stream 20.

[0068] The amount of flue gas 38 contained in the fully conditioned primary fuel stream 18 delivered to the combustion zone 24 will be in a range from about 80% to about 90% by volume, based on the total final volume of the fully conditioned primary fuel stream 18. The amount of flue gas 38 contained in the fully conditioned secondary fuel stream 20 delivered to the combustion zone 24 will be in a range from about 92% to about 94% by volume, based on the total final volume of the fully conditioned secondary fuel stream 20. The amount of flue gas 38 contained in the fully conditioned tertiary fuel stream 22 delivered to the combustion zone 24 will be in a range from about 94% to about 96% by volume, based on the total final volume of the fully conditioned tertiary fuel stream 22.

[0069] In addition to significantly increasing the amount of gaseous combustion products 38 entrained in and mixed with the secondary and tertiary streams 20 and 22, the burner apparatus 2 of the present invention provides further enhanced internal flue gas recirculation (IFGR) by reducing the amount of fuel that must be used in the fuel-rich primary fuel stream 18 to stabilize the combustor combustion zone 24 and the combustor flame. This is due to the fact that, unlike existing combustors, the stability of the secondary and tertiary fuel streams is also greatly enhanced by the placement of protrusions or other radially external impingement structures 82, 80, 78, 76, and / or 74 in the flow paths 52 and 54 of these fuel streams, as well as the forward impingement protrusion 72 at the forward end 30 of the combustor wall 10.

[0070] Therefore, the present invention is well suited to achieve the above-mentioned objectives and attain the purposes and advantages mentioned above and those inherent therein. Although presently preferred embodiments and procedures have been described for purposes of this disclosure, the present invention is not limited in its application to the details of these preferred embodiments and procedures. Many changes and modifications will be apparent to those skilled in the art. Such changes and modifications are intended to be encompassed by the present invention as defined in the claims. Furthermore, unless expressly stated otherwise, the phraseology and terminology employed herein are for purposes of description and not of limitation.

Claims

1. A burner device for discharging a burner flame in a heating system having gaseous combustion products therein, the burner device comprising: a burner wall having a forward longitudinal end and an exterior; a flow passage for air or other oxygen source, said flow passage extending through said burner wall and at least substantially surrounded by said burner wall, said flow passage having a discharge at said forward longitudinal end of said burner wall; a combustion zone of the burner apparatus, the combustion zone having a starting end located substantially at the front longitudinal end of the burner wall; a series of primary fuel injection structures located exterior to the flow passage and at least partially surrounding the flow passage, the primary fuel injection structures being located rearwardly and radially outwardly of the forward longitudinal end of the combustor wall, and each of the primary fuel injection structures being oriented to inject a stream of primary fuel along a primary fuel flow path exterior to the combustor wall and toward the combustion zone; at least one primary radial impingement structure disposed on the exterior of the combustor wall and in the primary fuel flow path for contacting at least a portion of the primary fuel stream injected by each of the primary fuel injection structures; a series of secondary fuel injection structures located outside of the flow passage and at least partially surrounding the flow passage, the secondary fuel injection structures being located rearwardly and radially outwardly of the primary fuel injection structure and each of the secondary fuel injection structures being oriented to inject a stream of secondary fuel along a secondary fuel flow path external to the combustor wall toward the combustion zone; as well as at least one secondary radial impingement structure disposed on the exterior of the combustor wall and located rearward of the at least one primary radial impingement structure in the secondary fuel flow path for contacting at least a portion of the secondary fuel stream injected by each of the secondary fuel injection structures; wherein the at least one primary radial impingement structure on the exterior of the combustor wall is also located in the secondary fuel flow path for contacting at least a portion of the secondary fuel flow injected by each of the secondary fuel injection structures.

2. The burner device according to claim 1, wherein: The at least one primary radial striking structure is a front primary radial striking structure, and The burner apparatus further includes a rear primary radial impingement structure disposed on the exterior of the burner wall and located rearward of the front primary radial impingement structure in the primary fuel flow path for contacting at least a portion of the primary fuel flow injected by each of the primary fuel injection structures.

3. The burner apparatus according to claim 2, wherein: The at least one secondary radial impact structure is a forward secondary radial impact structure, and The burner apparatus further includes a rear secondary radial impingement structure disposed on the exterior of the burner wall and located rearward of the front secondary radial impingement structure in the secondary fuel flow path for contacting at least a portion of the secondary fuel flow injected by each of the secondary fuel injection structures.

4. The burner device according to claim 3, wherein The forward and aft primary radial impingement structures on the exterior of the combustor wall are also located in the secondary fuel flow path for contacting at least a portion of the secondary fuel flow injected by each of the secondary fuel injection structures.

5. The burner apparatus according to claim 4, wherein: the forward primary radial impingement structure on the exterior of the combustor wall being the forward longitudinal end of the combustor wall body; the rear primary radial impingement structure being a radial protrusion formed on the exterior of the combustor wall and having an outer diameter or width greater than an outer diameter or width of the forward longitudinal end of the combustor wall; the forward secondary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and having an outer diameter or width greater than the outer diameter or width of the aft primary radial impingement structure; and The rear secondary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and has an outer diameter or width greater than the outer diameter or width of the front secondary radial impingement structure.

6. The burner device according to claim 3, wherein The primary fuel injection structure is located in or at least partially forward of an opening provided in a front face of the front secondary radial impingement structure.

7. The burner apparatus according to claim 1, wherein The combustion zone is a single-stage combustion zone having only one combustion stage for combusting both the primary fuel flow injected from the primary fuel injection structure and the secondary fuel flow injected from the secondary fuel injection structure.

8. The burner apparatus of claim 1 , wherein: said at least one primary radial impingement structure on said exterior of said combustor wall being said forward longitudinal end of said combustor wall; the primary fuel flow path being oriented to deliver at least a portion of the primary fuel flow injected from each of the primary fuel injection structures to the starting end of the combustion zone; as well as The secondary fuel flow path is oriented to deliver at least a portion of the secondary fuel flow injected from each of the secondary fuel injection structures to the starting end of the combustion zone.

9. The burner apparatus of claim 1 , wherein: The primary fuel injection structures in the series of primary fuel injection structures are separated by gap regions between the primary fuel injection structures, and The secondary fuel flow path for the secondary fuel flow injected from the secondary fuel injection structures is directed toward or across the gap region between the primary fuel injection structures.

10. The burner apparatus of claim 1 , further comprising: a series of tertiary fuel injection structures located outside of the flow passage and at least partially surrounding the flow passage, the tertiary fuel injection structures located rearwardly and radially outwardly of the secondary fuel injection structures, and each of the tertiary fuel injection structures oriented to inject a stream of tertiary fuel along a tertiary fuel flow path outside of the combustor wall toward the combustion zone; as well as At least one tertiary radial impingement structure is disposed on the exterior of the combustor wall and located behind the at least one secondary radial impingement structure in the tertiary fuel flow path for contacting at least a portion of the tertiary fuel flow injected by each of the tertiary fuel injection structures.

11. The burner device according to claim 10, wherein The at least one secondary radial impingement structure on the exterior of the combustor wall is also located in the tertiary fuel flow path for contacting at least a portion of the tertiary fuel flow injected by each of the tertiary fuel injection structures.

12. The burner apparatus according to claim 10, wherein The at least one primary radial impingement structure on the exterior of the combustor wall body is also located in the tertiary fuel flow path for contacting at least a portion of the tertiary fuel flow injected by each of the tertiary fuel injection structures.

13. The burner apparatus of claim 10, wherein: the at least one primary radial impact structure being a forward primary radial impact structure; The burner apparatus further includes a rear primary radial impingement structure disposed on the exterior of the burner wall and located rearward of the front primary radial impingement structure in the primary fuel flow path for contacting at least a portion of the primary fuel stream injected by each of the primary fuel injection structures; the at least one secondary radial impact structure being a forward secondary radial impact structure; The burner apparatus further includes a rear secondary radial impingement structure disposed on the exterior of the burner wall and located rearward of the front secondary radial impingement structure in the secondary fuel flow path for contacting at least a portion of the secondary fuel flow injected by each of the secondary fuel injection structures; The at least one tertiary radial impact structure is a forward tertiary radial impact structure; and The combustor apparatus further includes a rear tertiary radial impingement structure disposed on the exterior of the combustor wall and located rearward of the forward tertiary radial impingement structure in the tertiary fuel flow path for contacting at least a portion of the tertiary fuel flow injected by each of the tertiary fuel injection structures.

14. The burner apparatus of claim 13, wherein: the forward and aft primary radial impingement structures on the exterior of the combustor wall also being located in the secondary fuel flow path for contacting at least a portion of the secondary fuel stream injected by each of the secondary fuel injection structures; the forward and aft secondary radial impingement structures on the exterior of the combustor wall also being located in the tertiary fuel flow path for contacting at least a portion of the tertiary fuel stream injected by each of the tertiary fuel injection structures; and The forward and aft primary radial impingement structures on the exterior of the combustor wall are also located in the tertiary fuel flow path for contacting at least a portion of the tertiary fuel flow injected by each of the tertiary fuel injection structures.

15. The burner apparatus of claim 14, wherein: The front primary radial impingement structure on the exterior of the burner wall is the front longitudinal end of the burner wall; the rear primary radial impingement structure is a radial protrusion formed on the exterior of the burner wall and having an outer diameter or width greater than the outer diameter or width of the front longitudinal end of the burner wall; The forward secondary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and having an outer diameter or width greater than the outer diameter or width of the aft primary radial impingement structure; The rear secondary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and having an outer diameter or width greater than the outer diameter or width of the front secondary radial impingement structure; the forward tertiary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and having an outer diameter or width greater than the outer diameter or width of the aft secondary radial impingement structure; and The rear tertiary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and having an outer diameter or width greater than that of the front tertiary radial impingement structure.

16. The burner apparatus of claim 13, wherein: The primary fuel injection structure is located in or at least partially forward of an opening provided in a front wall of the front secondary radial impingement structure, and The secondary fuel injection structure is located in or at least partially forward of an opening provided in a front wall of the front tertiary radial impingement structure.

17. The burner apparatus of claim 10, wherein: primary fuel injection structures in the series of primary fuel injection structures are separated by gap regions between the primary fuel injection structures; the secondary fuel flow path for the secondary fuel flow injected from the secondary fuel injection structures being directed toward or across the gap region between the primary fuel injection structures; secondary fuel injection structures in the series of secondary fuel injection structures are separated by gap regions between the secondary fuel injection structures; and The tertiary fuel flow path for the tertiary fuel flow injected from the tertiary fuel injection structures is directed toward or across the gap region between the secondary fuel injection structures.

18. The burner apparatus according to claim 10, wherein The combustion zone is a single-stage combustion zone having only one combustion stage for combusting the primary fuel flow injected from the primary fuel injection structure, the secondary fuel flow injected from the secondary fuel injection structure, and the tertiary fuel flow injected from the tertiary fuel injection structure.

19. The burner apparatus of claim 10, wherein: said at least one primary radial impingement structure on said exterior of said combustor wall being said forward longitudinal end of said combustor wall body; the primary fuel flow path being oriented to deliver at least a portion of the primary fuel flow injected from each of the primary fuel injection structures to the starting end of the combustion zone; the secondary fuel flow path being oriented to deliver at least a portion of the secondary fuel flow injected from each of the secondary fuel injection structures to the starting end of the combustion zone; as well as The tertiary fuel flow path is oriented to deliver at least a portion of the tertiary fuel flow injected from each of the tertiary fuel injection structures to the starting end of the combustion zone.

20. A method for reducing NO from burner equipment x The method of discharge comprises the following steps: a) discharging air or other oxygen source into the combustion zone from a discharge opening of a flow passage at least partially surrounded by a burner wall, the discharge opening of the flow passage being located at a forward end of the burner wall, the burner wall having an exterior, and the combustion zone having a starting end located substantially at the forward end of the burner wall; b) injecting primary fuel streams from a plurality of primary fuel injection structures on the exterior of the combustor wall toward the combustion zone, wherein at least a portion of each of the primary fuel streams contacts at least one primary radial impingement structure disposed on the exterior of the combustor wall; and c) injecting secondary fuel streams from a plurality of secondary fuel injection structures on the exterior of the combustor wall toward the combustion zone, wherein the secondary fuel injection structures are located rearwardly and radially outwardly of the primary fuel injection structure, and at least a portion of each of the secondary fuel streams contacts at least one secondary radial impingement structure disposed on the exterior of the combustor wall and located rearwardly of the at least one primary radial impingement structure.

21. The method according to claim 20, wherein At least a portion of each of the secondary fuel streams injected in step (c) also contacts the at least one primary radial impingement structure.

22. The method of claim 20, wherein: said at least one primary radial impingement structure being said leading end of said combustor wall; at least a portion of each of the primary fuel streams injected in step (b) also contacts a rear primary radial impingement structure disposed on the exterior of the combustor wall rearward of the forward end of the combustor wall; The at least one secondary radial strike structure is a forward secondary radial strike structure; and At least a portion of each of the secondary fuel streams injected in step (c) also contacts a rear secondary radial impingement structure disposed on the exterior of the combustor wall rearward of the front secondary radial impingement structure.

23. The method of claim 22, wherein: At least a portion of each of the secondary fuel streams injected in step (c) also contacts the rear primary radial impingement structure, and subsequently At least a portion of each of the secondary fuel streams also contacts the leading end of the combustor wall.

24. The method of claim 22, wherein: The rear primary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and having an outer diameter or width greater than an outer diameter or width of the front end of the combustor wall; the forward secondary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and having an outer diameter or width greater than the outer diameter or width of the aft primary radial impingement structure; and The rear secondary radial impingement structure is a radial protrusion formed on the exterior of the combustor wall and has an outer diameter or width greater than the outer diameter or width of the front secondary radial impingement structure.

25. The method according to claim 20, wherein The combustion zone has only a single combustion stage, and both the primary fuel stream and the secondary fuel stream are delivered to and combusted in the single combustion stage.

26. The method of claim 20, wherein: At least a portion of each of the primary fuel streams is delivered to and combusted at the starting end of the combustion zone, and At least a portion of each of the secondary fuel streams is delivered to the starting end of the combustion zone and combusted there.

27. The method according to claim 20, wherein The secondary fuel flow is injected from the secondary fuel injection structures toward or across gap regions between the primary fuel injection structures.

28. The method according to claim 20, further comprising the steps of: A tertiary fuel stream is injected from a plurality of tertiary fuel injection structures on the exterior of the combustor wall toward the combustion zone, wherein the tertiary fuel injection structures are located rearwardly and radially outwardly of the secondary fuel injection structures, and at least a portion of each of the tertiary fuel streams contacts at least one tertiary radial impingement structure disposed on the exterior of the combustor wall, and the at least one tertiary radial impingement structure is located rearwardly of the at least one secondary radial impingement structure.

29. The method of claim 28, wherein: at least a portion of each of said secondary fuel streams also contacts said at least one primary radial impingement structure; at least a portion of each of said tertiary fuel streams also contacts said at least one secondary radial impingement structure; and At least a portion of each of the tertiary fuel streams also contacts the at least one primary radial impingement structure.

30. The method of claim 28, wherein: said at least one primary radial impingement structure being said leading end of said combustor wall; at least a portion of each of said primary fuel streams also contacts an aft primary radial impingement structure disposed on said exterior of said combustor wall aft of said forward end of said combustor wall; the at least one secondary radial impact structure being a forward secondary radial impact structure; at least a portion of each of said secondary fuel streams also contacts an aft secondary radial impingement structure disposed on said exterior of said combustor wall aft of said forward secondary radial impingement structure; The at least one tertiary radial impact structure is a forward tertiary radial impact structure; and At least a portion of each of the tertiary fuel streams also contacts an aft tertiary radial impingement structure disposed on the exterior of the combustor wall aft of the forward tertiary radial impingement structure.

31. The method of claim 30, wherein: at least a portion of each of said secondary fuel streams also contacts said aft primary radial impingement structure; at least a portion of each of said secondary fuel streams also contacts said forward end of said combustor wall; at least a portion of each of said tertiary fuel streams also contacts said aft secondary radial impingement structure; and At least a portion of each of the tertiary fuel streams also contacts the forward secondary radial impingement structure.

32. The method of claim 28, wherein: The combustion zone has only a single combustion stage, and the primary fuel stream, the secondary fuel stream, and the tertiary fuel stream are all delivered to and combusted in the single combustion stage.

33. The method of claim 28, wherein: at least a portion of each of said primary fuel streams is delivered to said starting end of said combustion zone and combusted at said starting end; at least a portion of each of the secondary fuel streams is delivered to and combusted at the starting end of the combustion zone; and At least a portion of each of the tertiary fuel streams is delivered to the starting end of the combustion zone and combusted thereat.

34. The method of claim 28, wherein: The secondary fuel stream is injected from the secondary fuel injection structure toward or across the gap region between the primary fuel injection structures; and The tertiary fuel flow is injected from the tertiary fuel injection structure toward or across the gap region between the secondary fuel injection structures.

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